This invention relates to dump pots or transfer pots for carrying viscous materials. Particularly, this invention relates to drain valves on such transfer pots. More particularly, the invention relates to pivoting gate valves for use in controlling the flow of viscous materials from dump pots.
In the manufacture of many materials, viscous raw materials and intermediate products are commonly used or produced. For example, in the manufacture of chewing gum, a viscous gum base material is produced as an intermediate product. At a stage in the gum manufacturing process, the viscous gum base material is loaded into transport pots. The transport pots are used to carry the gum base material from one point to another point in the manufacturing process. The gum base material is typically made in a mixing kettle and then dumped into a transport pot. This pot is then transported by fork truck to processing machines. The transport pot has a valve at the bottom which is used to regulate the flow of material out of the transport pot. The valve is manually opened to transfer the gum base to processing machinery that will shape and form the gum base into pellets that are appropriate for the marketplace.
Typically, the transport pots are heated vessels, heated by such means as steam jacketing. The heat is required to maintain the transported material in a flowable state. Such highly viscous material as gum base may harden and become elastic as it cools, which is undesirable to occur in the transport pot. This is also a problem after transferring gum base from the transport pots to the processing machines, when the drain valves are manually closed. These conventional drain valves do not always close well and the gum base material drips from the valve and cools, thereby forming "strings" of gum base material that hang below the transport pots from the valves. These "strings" may drag on the factory floor and must be manually removed for sanitary reasons.
Many valves currently in use in such service at the drain of a transport pot are not well-suited for use with such viscous-heated materials. Some valves include a packing material that cannot withstand the high temperatures required to keep such viscous materials as thermoplastic adhesive or gum bases in a flowable form. Other valves have intricate shapes, pockets and crevices in which the viscous material may collect. It may be difficult to remove the viscous material from these hidden areas with the result that the material builds up and prevents the valves from operating properly.
Accordingly, there is a need for a drain valve for use on a transfer pot carrying hot viscous materials. Further, there is a need for such a drain valve that cleanly and securely closes against the viscous material and greatly reduces the formation of "strings".